The dielectric relaxation spectrum of poly(N‐vinylcarbazole) (PVK) and poly(3‐chloro‐N‐vinylcarbazole) (CLPVK) have been investigated in the temperature range −180–+240 °C. Four relaxations are observed in PVK. The α relaxation (225 °C) is associated with the glass transition of the polymer. On the basis of oxygen‐sorption experiments, the γ relaxation (∼−60 °C) has been associated with a rotational libration of the pendant carbazole group. It is also speculated on the basis of this work that an off‐axis dipole is induced in the carbazole moiety by the sorbed O2 producing the dielectrically active motion about the symmetry axis of the carbazole moiety. The β (∼80 °C) and the δ (∼−160 °C) relaxations are assigned as carbazole wagging motions and localized backbone motions, respectively. These assignments are based on comparative work in the literature.

The dielectric behavior of poly(acrylonitrile) (PAN) has been investigated through the formation of electrically polarized films. The formation of films having a persistent electrical polarization has been achieved by the application of electric fields of the order 104 V cm−1 at temperatures ranging from 130 to 160 °C. The thermally stimulated discharge spectrum of PAN reveals at least three different peaks, two of which might be related to the relaxation of oriented nitrile side groups (90 and 145 °C). Intense current peaks observed above 160 °C are believed to be associated with backbone mobility in amorphous and paracrystalline regions. It is suggested that nitrile orientation with an applied electric field results in the formation of a highly developed level of intermolecular bonding.

Considerable discrepancy exists in the recent literature on the assignments of the rotatory lattice modes of the n‐alkanes and polyethylene. New low‐temperature Raman data are presented on orthorhombic n‐alkanes and and on n‐C36D74 and n‐C16D34. Analyses of these data and the existing assignments show that the long‐axis rotatory mode of the triclinic n‐alkanes may be assigned to a weak Raman band at ∼ 50 cm−1; the Ag rotatory mode of polyethylene may be assigned to the Raman band at ∼ 130 cm−1 and the B3g rotatory mode to a weak Raman band at 108 cm−1.

The tensile stress‐strain behavior of PC was measured in mixtures of He, which is inert, and each of the following crazing agents: N2, Ar, and O2 at partial pressures of 0–1 atm and in the temperature range above 77 K. The yield point for crazing depends on temperature, pressure, and the shear yield point according to the following equation: σc/σs= (P exp(Q/RT)/P*)−1/12, where Q and P* depend on the gas. The values of Q are approximately the same as those for the adsorption and absorption energies as determined by theories and experiments. The maximum sensitivity of the craze yield point to the partial pressure of the crazing gas occurs at the lowest pressure for crazing. In the case of N2, a 1% change in the partial pressure can produce about a 0.45‐ksi change in the yield point.

In this study, optical microscopy,differential scanning calorimetry, and infrared spectroscopy are used to study the high‐temperature isothermal crystallization of high‐molecular‐weight poly(vinylidene fluoride). It is shown that there exists a temperature domain in which both the α and β phases of PVF2 can be grown concurrently and in competition with each other to form two distinct populations of spherulites which are characterized by different diameters, band periods, and melting points. In addition, a time‐ and temperature‐dependent crystal‐crystal transition from the α phase to the γ form can be induced in this high‐temperature crystallization region to produce spherulites which melt 15–20 ° above the melting point of the original α phase. This transformation exhibits nucleation and propagation characteristics which in some regions can compete with the normal growth of the α phase to produce unique ’’wagon‐wheel’’ spherulitic structures.

Normal mode calculations show that a single conformational defect in an otherwise all‐trans n‐alkane molecule disrupts the longitudinal acoustic mode (LAM) associated with the all‐trans molecule. Similar calculations for a chain in the conformation produced by smoothly twisting a planar zigzag through 180 ° about the chain axis show that the LAM amplitudes and frequencies are unaffected by this gentle twist. These calculations indicate that the decrease in the LAM intensity observed in some polyethylene samples cannot be accounted for by smoothly twisted chains, but can be accounted for by defects which involve large localized departures from the all‐trans conformation.

Commerical and experimental urethane polymers were studied by thermal‐mechanical methods including DSC and stress‐strain analysis. The studies reveal that following thermal treatment these polymers show time‐dependent mechanical properties. This time‐dependent period may be many days while the degree of this dependence is influenced by annealing temperature. By DSC analysis it has been shown that the glass transition temperature of the soft segment, Tgs, is also greatly influenced by annealing treatment. Immediately following annealing temperatures above 130 °C, Tgs may be as much as 40 °C higher than its ’’long‐time’’ value. With time, however, Tgs decreases to its original value. Higher‐temperature endothermic behavior associated with hard‐segment domains is also time dependent. Both the degree of Tgs shift and higher endothermic effects are correlated with annelaing temperature. The time‐dependent behavior for a given annealing temperature has been related to to chemical structure (ester vs ether, and hydrogen bonding effects). The data are explained in terms of the thermal stability of domains.

Davies and Jones have shown that if the configurational state of a liquid is determined by two or more order parameters that freeze in at the glass transition temperature Tg(P), the Ehrenfest relation, r=ΔβΔCp/TV (Δα)2=1, valid if there is one such parameter, is converted to an inequalityr?1. DiMarzio has shown correctly that if the conditions ΔS=0 and ΔV=0 are satisfied at Tg(P), r=1 regardless of the number of order parameters. He has, therefore, concluded that if experimentally r≳1, the order‐parameter concept is inapplicable to the glass transition. It is shown here that r≳1 implies that ΔS and ΔV cannot both be zero at Tg(P), and that there is extensive experimental evidence that the volumes of glasses depend on the pressure under which they were formed, implying ΔV≠0. It is concluded that the experimental observation r≳1 does not render the order‐parameter concept inapplicable.

A study has been made on the compatibility, thermal behavior, and mechanical properties of the system poly(vinyl chloride) and a copolyester thermoplastic elastomer (under the trade name of Hytrel by duPont). Results from NMR, linear thermal expansion, tensile test, and dynamic mechanical measurements indicate extensive mixing of PVC and the soft segments of the thermoplastic elastomer when the mixture is rapidly cooled from around 150 °C to ambient temperature. The hard segments of the elastomercrystallize under these conditions, as revealed by the calorimetric measurements. Upon isothermal annealing at 130 °C the mixture shows signs of phase separation in dynamic mechanical measurements. These observations suggest the existence of upper critical solution temperatures for the system. The associated miscibility gap encompasses room temperature and reaches a maximum temperature somewhere between 130 and 150 °C. The phase domains in the annealed sample are extremely fine and have been estimated to be no more than 100 Å in size from the pulsed NMR data.

Proton spin‐spin (T2) and spin‐lattice (T1) relaxation times have been measured in order to elucidate the molecular dynamics in poly(N‐vinylcarbazole) (PVK). Measurements were obtained on samples covering a broad range of molecular weights in air, O2, N2, and invacuo. Correlation frequencies νc determined from NMR data were used in conjunction with dielectric data to construct transition maps. The α,β relaxations associated with main‐chain and segmental motion exhibit temperature‐dependent behavior very similar to that observed in polystyrene (PS). The γ relaxation in PVK is highly unusual in that it is dielectrically active and manifested in the T2 data only in the presence of O2. A detailed interpretation of this effect is provided, leading to the conclusion that O2diffusion is severely restricted at low temperatures and that torsional oscillation of the carbazole group is responsible for the γ relaxation. It is proposed that the presence of O2 leads to relaxation by slow spin diffusion to the paramagnetic site at low temperatures but by direct paramagneticrelaxation by diffusing O2 molecules at high temperatures. This effect is related to the temperature‐dependent lifetime of the O2‐carbazole complex.

The internal microstructure of large melt‐grown paraffin (n‐eicosane, C20H42) single crystals was examined by the Lang x‐ray diffraction projection topographic technique. Crystal selection was facilitated by use of an electro‐optical system which permitted instantaneous display of Laue transmission x‐ray diffraction patterns on a television monitor. The crystals were oriented and topographic diffraction planes were selected by the use of a standard (001) stereographic projection plotted from computed angles between crystallographic planes. A second electro‐optical system which permitted direct viewing of the topographic images was use for rapid alignment of the Lang camera and ensured uniformly exposed topographs. X‐ray topographs were obtained from crystals in the as‐grown, plastically deformed, and γ‐irradiated states. The results indicate that both plastic deformation and γ irradiation caused marked changes in the microstructure of the crystals, and that x‐ray topography can be successfully exploited to determine such changes in hydrocarbon crystals.

In order to minimize the occurrence of heterogeneities, or segregation, of polyethylene and poly(ethylene‐d4) in mixed‐crystal systems during melt crystallization, it has been found that conditions of high molar ratio of PEH/PED and a small difference in melting points between the two species are necessary. Under these optimum conditions the infrared spectral results observed in melt‐crystallized polyethylene have to be attributed predominantly to chains which fold essentially with adjacent reentry along (200) planes.

The normal vibrations of crystalline trans‐1,4‐polybutadiene have been calculated by combining interchain atom‐atom potentials with the previously proposed intrachain force field. These calculations have been used to analyze the infrared and Raman spectra of an essentially all‐trans urea‐complex polymer. The band splittings and low‐frequency lattice modes observed in these spectra are satisfactorily accounted for by the calculations.

The superstructure of PPO/iPS blends, in which the iPS is partially crystallized from the glassy state by thermal treatment, is studied as a function of composition. A superstructure model, based on Hosemann’s treatment of a linear paracrystalline lattice, is used in order to calculate theoretical SAXS curves and fit them with experimental SAXS data. The model includes such superstructure parameters as lamellae thicknesses, thicknesses of amorphous regions, thickness distribution function, and size and shape of ’’ordered’’ regions. It is found that the lattice thickness distribution functions for both the crystalline lamellae and amorphous layers are best represented by symmetrical Gaussian functions. The thickness of the iPS crystal lamellae decreases with increasing PPO content. This explains, in part, the observed decrease of the melting point of the iPS in these blends.

PPO/iPS blends of various compositions have been crystallized isothermally and by solvent‐induced treatment from the glassy state. The crystallinity as a function of composition has been determined from the integral scattering of the crystalline and amorphous regions. Applying Hosemann’s concept of the paracrystal, crystallite size and strain parameters have been calculated from peak broadening analysis. The results are compared to those obtained from DSC and small‐angle x‐ray measurements on the same samples.

The total polarization due to molecular dipoles in a glassy electret is computed using an Onsager cavity approach. From this result, all the possible contributions to the piezoelectric and pyroelectric coefficients are considered. It is shown that there are major contributions from the variation in dielectric constant and, for pyroelectricity, from thermal motion. These results account well for experimental data for polyvinyl chloride.

A site model has been used in conjuction with potential‐energy calculations to examine the role of isolated molecules with methyl branches in the mechanical relaxations of a linear hydrocarbon host crystal. The results indicate that there are two possible relaxation modes and that the one involving molecular rotation is energetically favorable over the one involving rotation and translation. For some modes of deformation, the calculated relaxation strengths are comparable to the experimentally measured ones. Furthermore, the barriers determined in this work yield calculated curves of the logarithmic decrement as a function of temperature which are comparable to the experimental ones. The relaxation is much weaker for unbranched chains in the planar zigzag conformation.

A hybrid Ising mean‐field model is developed to account for the conformational and configurational origins of transitions in dense chain molecular fluids. The model is applied to polymethylene. The role of intermolecular interactions in controlling both the melt transition temperature and the extent of the degree of cooperativity is demonstrated. Near quantitative agreement of the transition‐temperature and heat‐capacity behavior is achieved when a linear correction term to describe interchain melting is incorporated in the general model.

In order to obtain information concerning the effect of molecular weight on the molecular mobility involved in the relaxation processes associated with the nonequilibrium thermodynamic state of glassy polymers, enthalpy‐relaxation studies have been undertaken on glassy atactic polystyrenes of various molecular weights, ranging from 2.0×103 to 811×103. As was found in previous studies of enthalpy relaxation in organic glasses, the glass transition temperature Tg is the principal rate‐determining factor. From a more detailed analysis of the data, however, it is evident that the relaxation processes at corresponding temperature intervals below Tg are a function of the molecular weight. The relaxation rate decreases somewhat with increasing molecular weight and approaches a limiting value at molecular weights in the vicinity of 50×103, the critical molecular‐weight range in the molecular‐weight dependence of glass transformation. For Aroclor 5460, a nonpolymeric material of lower molecular weight but having a Tg comparable to that of atactic polystyrene of molecular weight 2.0×103, a slightly faster relaxation rate was observed.

Inferring a relaxation spectrum from mechanical test data was approached as a mathematically ill‐posed or incorrectly formulated problem in the Tikhonov sense. A compound technique presented previously by the authors, which incorporates Tikhonov’s regularization ideas into quadratic programming, was successfully applied to the inversion of the Fredholm integral equations of the first kind encountered in the theory of linear viscoelasticity. Very good results were obtained when computer‐simulated data from initially assumed unimodal and symmetrical bimodal distributions were used.